In recent years, climate change concerns, reductions in costs, governmental initiatives, and other factors have driven a rapid rise in the installation of renewable energy generation (EG) systems (i.e., systems that generate energy using renewable resources such as solar, wind, hydropower, etc.) at residential and non-residential sites. Solar photovoltaic (PV) systems, in particular, have been very popular EG systems.
PV systems include PV modules that generate direct current (DC) power from photons emitted from the sun. When strung together in series, the string of PV modules will have a high DC voltage equal to the sum of the PV module DC voltage. In systems that utilize centralized or so-called string inverters, the combined DC power output of a group of serially connected modules is converted into alternating current (AC) power by the inverter for use by a load, such as a residential appliance, commercial tool, the utility grid and the like. String and central inverters can take one or more PV module strings as input in order to increase the amount of available DC power to converter into AC power. The inverter must be matched to the DC and AC power in order to maximize inversion efficiency. However, manufacturing costs prevent string inverters from being able to be precisely matched to the power out of a particular array. They often come in integer sizes such as 5 kW, 10 kW, etc., where that number represents the maximum capacity of the inverter. As a result, the particular string inverter used on any particular job may have quite a bit of excess capacity for which a return on investment is never achieved. Therefore, the one size fits all or relatively small numbers of sizes fits all approach to string inverters results in unnecessarily high hardware costs. One solution to overcome this limitation is through the use of micro inverters instead of string and central inverters. These micro inverters convert the DC power output of one to four modules into AC power within the string. This eliminates the sizing issue from above, but leads to increased equipment costs, maintenance complexity, and redundancy. Therefore, there exists a need for an inverter system that combines the lower cost of a string inverter with the efficient inverter to PV module sizing of the micro inverter.